The present invention relates to a bidirectional steerable catheter that permits asymmetrical deflection.
Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity.
In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is.
Steerable catheters are generally well-known. For example, U.S. Pat. No. RE 34,502 describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston and through the catheter body. The distal end of the puller wire is anchored in the tip section of the catheter. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the catheter tip section.
Bidirectional steerable catheter, i.e., a catheter that can be deflected in two directions, typically opposing directions, are also known. For example, U.S. Pat. No. 6,210,407 discloses a bidirectional steerable catheter having two puller wires extending through the catheter. The distal ends of the puller wires are anchored to opposite sides of the tip section of the catheter. A suitable bidirectional control handle is provided that permits longitudinal movement of each puller wire to thereby allow deflection of the catheter in two opposing directions.
It is often desirable to provide a bidirectional steerable catheter that can be deflected to form two different curves, i.e., two curves each having a different radius of curvature. Such designs are often preferred by physicians because it gives them a choice of curves during a procedure. Existing catheters achieve this result by having two puller wires with distal ends anchored at different positions along the length of the catheter.
The present invention is directed to a bidirectional steerable catheter that can be deflected to form two different curves, i.e., two curves each having a different radius of curvature. In accordance with the present invention, the catheter comprises an elongated, flexible tubular catheter body having proximal and distal ends and a lumen extending therethrough. A tip section is provided at the distal end of the catheter body. The tip section comprises a flexible plastic tubing having at least first and second off-axis lumens extending therethrough. A control handle is attached to the proximal end of the catheter body.
A first puller wire extends through the lumen of the catheter body and the first off-axis lumen of the tip section. The first puller wire has a distal end anchored in the tip section and a proximal end anchored to the control handle. A second puller wire extends through the lumen of the catheter body and the second off-axis lumen of the tip section. The second puller wire has a distal end anchored in the tip section and a proximal end anchored to the control handle.
A first compression coil extends through the lumen of the catheter body in surrounding relation to the first puller wire. The first compression coil has a distal end anchored in the catheter body or in the first off-axis lumen of the tip section at a first anchor position. A second compression coil extends through the lumen of the catheter body in surrounding relation to the second puller wire and into the second off-axis lumen. The second compression coil has a distal end anchored in the second off-axis lumen of the tip section at a second anchor position that is distal to the first anchor position. By this design, the radius of curvature of each curve achieved by deflection of the tip section is controlled by the anchor position of the compression coil surrounding the appropriate puller wire.